Perch Shop - Text Field in Cart or Checkout?

We have built a Perch site a while ago, using the Shop app for ordering flowers and gifts (checkout process can be seen here), and the client would like to be able to have the order include one to many message(s) attached to the flower order cart. Is it possible to have a text field input on either the cart or checkout levels? I seem to think the checkout form would support it, but not the cart (where the client would like the text message to be, as a user could be ordering more than one set of flowers in their order that needs a message attached).

One little problem I had was in modifying the order_paid.html template, I tried copying the template from perch/addons/apps/perch_shop/templates/shop/email to perch/templates/shop/email and Perch ignored any changes I made to it there. Is that a file I have to edit in place or is there a way to duplicate as a normal template that I am missing?

tried copying the template from perch/addons/apps/perch_shop/templates/shop/email to perch/templates/shop/email and Perch ignored any changes I made to it there. Is that a file I have to edit in place or is there a way to duplicate as a normal template that I am missing?

If you turn on debug mode and go to the email edit form on the control panel, you should be able to see the file path of the template being used in the debug message at the bottom.